1. Field of the Invention
This invention relates generally to the field of PEM (Proton Exchange Membrane, also known as Polymer Electrolyte Membrane) Fuel Cells, i.e., PEMFC. More specifically, the invention relates to a method of preparing Membrane Electrode Assembly, i.e., MEA for PEMFC.
2. Background of the Invention
Increasing investment is being directed into research for new materials and technologies for producing, storing, and using hydrogen as a renewable energy carrier. Hydrogen has implications to reduce dependence on oil as the primary transportation fuel source, to improve energy efficiency, and to address environmental concerns associated with the use of fossil fuel. Due to their high theoretical efficiency, polymer-electrolyte membrane-fuel cells (PEMFCs) will play a critical role as power sources in a hydrogen-based energy infrastructure.
The heart of a PEMFC is a 3-layer Membrane Electrode Assembly (MEA), consisting of anode, membrane electrolyte, and cathode, where hydrogen and oxygen are catalytically converted into water and electricity. The operating conditions and performance characteristics of PEMFCs make them currently the most attractive fuel cell technology for use in automotive and stationary applications. Currently, PEMFCs face severe performance and durability challenges associated with their materials and components. Among them is the performance of the cathode electrocatalyst, the location of molecular oxygen and proton conversion to water by the oxygen reduction reaction (ORR). Various Pt-based catalysts have been used as the ORR cathode electrocatalysts in fuel cells. Catalyst performance is generally expressed as the ratio between the catalytic oxygen reduction activity (cell current at given cell potential) and the cost (equivalent to the employed mass) of the platinum electrocatalysts at the PEMFC cathode. This ratio is generally referred to as the cathode Pt mass activity. It has been estimated that the cathode Pt mass activity has to be improved by a factor of at least 4 compared to ˜45 wt % Pt/C standard catalyst before automotive PEMFC cost targets can be met.